碳氮源及pH调控对假肠膜明串珠菌产甘露醇的影响

Effect of carbon and nitrogen source and pH control strategy on mannitol production by Leuconostoc pseudomesenteroides G123

为了降低生物法制备甘露醇的成本,以假肠膜明串珠菌Leuconostoc pseudomesenteroides G123为研究对象,对培养基中的氮源、葡萄糖与果糖比例和p H调控过程进行了优化,提高了果糖转化率和甘露醇产量。5L发酵罐中结果显示:采用2g/L的酵母粉作为单一氮源,葡萄糖和果糖的比例为0.35∶1,初始p H值7.5,发酵过程中保持p H值不低于4.5,甘露醇产量可达57.24g/L,甘露醇对果糖的转化率为83.2%。该过程副产D-乳酸20.32g/L,其光学纯度达99.9%,具有回收价值,甘露醇与D-乳酸对糖总转化率为89.38%,有助于降低生物法制备甘露醇的成本。

A new mutant strain Leuconostoc pseudomesenteroides G123 was investigated in this study. The nitrogen source,the ratio of glucose and fructose and the p H control strategy were optimized to reduce the cost of mannitol production. Batch fermentations were operated in a 5L fermentor.The results showed that 57.24g/L mannitol was produced with the mannitol yield of 83.2% when 2g/L yeast extract was chosen as the single nitrogen source,the ratio of fructose toglucose was 0.35∶1,and the initial p H was controlled at 7.5 and kept constant at 4.5 in the later phase. Besides,20.32g/L D-lactic acid with optical purity of 99.9% was also produced which suggested it could be recovered as a by-product. The yield of mannitol and lactic acid to the total sugar was 89.38%. As a result,the cost was reduced efficiently.